A Las Vegas bachelor party turns bad as Phil (Bradley Cooper), Stu (Ed Helms) and Alan (Zach Galifianakis) wake up in a destroyed hotel room with a tiger, a baby and a missing tooth. No one can remember what happened the night before, and what's worse, the groom (Justin Bartha) is missing. They have less than 24 hours to find him and get to the wedding on time. Along the way, they discover evidence of their wild, drunken night, including Mike Tyson, a naked Asian gangleader and photos from an impromptu Las Vegas wedding.